Director Ava DuVernay is bringing the story of one of the most iconic, and violent, moments in the Civil Rights Movement to the screen with the help of some key producers and stars, like Oprah Winfrey.

Winfrey recently addressed the audience after the film premiered at AFI Fest this week. The film's producer and co-star let them know how she came to be a part of the movie everyone is buzzing about.

David Oyewelo "is the reason I came on board," Winfrey said of her co-star, who plays Dr. Martin Luther King, Jr. "David and I became fast friends when we did The Butler together and he told me that this had been his dream for a very long time."

At the request of Winfrey, Oyewelo joined the production team of the biopic and set out to tell the story of the 1965 marches from Selma to Montgomery.

The film was not an easy one to make. It required a lot of dedication from the cast to pull off this iconic moment in the Civil Rights Movement.

"[There were] hundreds and hundreds of extras wearing wool clothes in 104-degree heat walking across that bridge again and again and again," Winfrey said. "People were there doing it because they felt, first of all that they were a part of something that was bigger than they."

The subject matter of racial tensions was sometimes difficult for the cast to portray. Some extras were really uncomfortable shouting racial slurs like the N-word.

"I remember one woman saying, 'You really want me to say it out loud? You want me to say that word out loud?'" Winfrey said.

But the result was well worth a little discomfort. DuVernay's film is getting rave reviews from critics and it even holds a 100% rating on Rotten Tomatoes. Oyewelo says the production team of Oprah Winfrey and Brad Pitt are to thank for the movie's success.

"This is how you use power that has been afforded you," Oyewelo said. "To get things done that otherwise wouldn't be."